[PATCH v3 0/3] Fixes for console command line ordering

[PATCH v3 0/3] Fixes for console command line ordering

[Tony Lindgren]

Hi,

Recent changes to add support for DEVNAME:0.0 style consoles caused a
regression with the preferred console order where the last console on
the kernel command line is no longer the preferred console.

The following three changes fix the issue using Petr's suggestion that
does not involve calling __add_preferred_console() later on again, and
adds the deferred consoles to the console_cmdline[] directly to be
updated when the console is ready.

We revert the earlier printk related changes, and then add back the
DEVNAME:0.0 functionality based on Petr's code snippet. And we end up
reducing the code quite a bit too this way.

The reason we want DEVNAME:0.0 style consoles is it helps addressing the
console based on the connected serial port controller device rather than
using the hardcoded ttyS addressing. And that helps with issues related
to the console moving around after togging the HSUART option in the BIOS,
or when new ports are enabled in devicetree and aliases are not updated.

Regards,

Tony

Changes since v2:

- Use match_devname_and_update_preferred_console() naming and update
  the comments

- Add a patch to rename the serial functions to use match and update
  naming

- Use ttyname instad of chardev in console_setup()

- Split variables per-line in console_setup()

- Initialize idx to -1 for devname in console_setup()

- Add pr_info() statement when a preferred console is associated with
  a devname

Changes since v1:

- Revert the problem causing printk changes and switch to using the
  solution based on Petr's suggestion and code snippet

Tony Lindgren (3):
  printk: Revert add_preferred_console_match() related commits
  printk: Add match_devname_and_update_preferred_console()
  serial: core: Rename preferred console handling for match and update

 drivers/tty/serial/8250/8250_core.c  |   4 +-
 drivers/tty/serial/serial_base.h     |   4 +-
 drivers/tty/serial/serial_base_bus.c |  23 +++--
 include/linux/printk.h               |   5 +-
 kernel/printk/Makefile               |   2 +-
 kernel/printk/conopt.c               | 146 ---------------------------
 kernel/printk/console_cmdline.h      |   7 +-
 kernel/printk/printk.c               | 122 ++++++++++++++++------
 8 files changed, 111 insertions(+), 202 deletions(-)
 delete mode 100644 kernel/printk/conopt.c


base-commit: 6ba59ff4227927d3a8530fc2973b80e94b54d58f
-- 
2.45.2

[PATCH v3 1/3] printk: Revert add_preferred_console_match() related commits

[Tony Lindgren]

Recent changes to allow using DEVNAME:0.0 style console names caused a
regression to the kernel command line handling for the console options.

The last preferred console added gets used for init. This is documented
in the comments for add_preferred_console(). Now the kernel command line
options for console=ttyS0,115200 console=tty0 are wrongly handled and
cause the /dev/console to be associated with ttyS0 instead of tty0.

This happens because we are calling __add_preferred_console() later on
from serial8250_isa_init_ports() after console_setup() and the console
gets treated as the last added preferred console. As the DEVNAME:0.0 style
console device is not known at console_setup() time, I added a call to
__add_preferred_console() later on when the console is ready.

To fix the issue, let's revert the printk related commits:

f03e8c1060f8 ("printk: Save console options for add_preferred_console_match()")
b73c9cbe4f1f ("printk: Flag register_console() if console is set on command line")
8a831c584e6e ("printk: Don't try to parse DEVNAME:0.0 console options")

We need to also drop the call for add_preferred_console_match() from
serial_base_add_one_prefcon() added by commit 787a1cabac01 ("serial: core:
Add support for DEVNAME:0.0 style naming for kernel console").

Petr has suggested a better way to handle the deferred consoles that does
not rely on calling __add_preferred_console() again.

Reported-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/linux-serial/ZlC6_Um4P4b-_WQE@pathway.suse.cz/
Fixes: f03e8c1060f8 ("printk: Save console options for add_preferred_console_match()")
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Tony Lindgren <tony.lindgren@linux.intel.com>
---
 drivers/tty/serial/serial_base_bus.c |   8 +-
 include/linux/printk.h               |   3 -
 kernel/printk/Makefile               |   2 +-
 kernel/printk/conopt.c               | 146 ---------------------------
 kernel/printk/console_cmdline.h      |   6 --
 kernel/printk/printk.c               |  23 +----
 6 files changed, 6 insertions(+), 182 deletions(-)
 delete mode 100644 kernel/printk/conopt.c

diff --git a/drivers/tty/serial/serial_base_bus.c b/drivers/tty/serial/serial_base_bus.c
index 73c6ee540c83..5ebacb982f9e 100644
--- a/drivers/tty/serial/serial_base_bus.c
+++ b/drivers/tty/serial/serial_base_bus.c
@@ -210,13 +210,7 @@ void serial_base_port_device_remove(struct serial_port_device *port_dev)
 static int serial_base_add_one_prefcon(const char *match, const char *dev_name,
 				       int port_id)
 {
-	int ret;
-
-	ret = add_preferred_console_match(match, dev_name, port_id);
-	if (ret == -ENOENT)
-		return 0;
-
-	return ret;
+	return 0;
 }
 
 #ifdef __sparc__
diff --git a/include/linux/printk.h b/include/linux/printk.h
index 40afab23881a..65c5184470f1 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -60,9 +60,6 @@ static inline const char *printk_skip_headers(const char *buffer)
 #define CONSOLE_LOGLEVEL_DEFAULT CONFIG_CONSOLE_LOGLEVEL_DEFAULT
 #define CONSOLE_LOGLEVEL_QUIET	 CONFIG_CONSOLE_LOGLEVEL_QUIET
 
-int add_preferred_console_match(const char *match, const char *name,
-				const short idx);
-
 extern int console_printk[];
 
 #define console_loglevel (console_printk[0])
diff --git a/kernel/printk/Makefile b/kernel/printk/Makefile
index 040fe7d1eda2..39a2b61c7232 100644
--- a/kernel/printk/Makefile
+++ b/kernel/printk/Makefile
@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-only
-obj-y	= printk.o conopt.o
+obj-y	= printk.o
 obj-$(CONFIG_PRINTK)	+= printk_safe.o nbcon.o
 obj-$(CONFIG_A11Y_BRAILLE_CONSOLE)	+= braille.o
 obj-$(CONFIG_PRINTK_INDEX)	+= index.o
diff --git a/kernel/printk/conopt.c b/kernel/printk/conopt.c
deleted file mode 100644
index 9d507bac3657..000000000000
--- a/kernel/printk/conopt.c
+++ /dev/null
@@ -1,146 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Kernel command line console options for hardware based addressing
- *
- * Copyright (C) 2023 Texas Instruments Incorporated - https://www.ti.com/
- * Author: Tony Lindgren <tony@atomide.com>
- */
-
-#include <linux/console.h>
-#include <linux/init.h>
-#include <linux/string.h>
-#include <linux/types.h>
-
-#include <asm/errno.h>
-
-#include "console_cmdline.h"
-
-/*
- * Allow longer DEVNAME:0.0 style console naming such as abcd0000.serial:0.0
- * in addition to the legacy ttyS0 style naming.
- */
-#define CONSOLE_NAME_MAX	32
-
-#define CONSOLE_OPT_MAX		16
-#define CONSOLE_BRL_OPT_MAX	16
-
-struct console_option {
-	char name[CONSOLE_NAME_MAX];
-	char opt[CONSOLE_OPT_MAX];
-	char brl_opt[CONSOLE_BRL_OPT_MAX];
-	u8 has_brl_opt:1;
-};
-
-/* Updated only at console_setup() time, no locking needed */
-static struct console_option conopt[MAX_CMDLINECONSOLES];
-
-/**
- * console_opt_save - Saves kernel command line console option for driver use
- * @str: Kernel command line console name and option
- * @brl_opt: Braille console options
- *
- * Saves a kernel command line console option for driver subsystems to use for
- * adding a preferred console during init. Called from console_setup() only.
- *
- * Return: 0 on success, negative error code on failure.
- */
-int __init console_opt_save(const char *str, const char *brl_opt)
-{
-	struct console_option *con;
-	size_t namelen, optlen;
-	const char *opt;
-	int i;
-
-	namelen = strcspn(str, ",");
-	if (namelen == 0 || namelen >= CONSOLE_NAME_MAX)
-		return -EINVAL;
-
-	opt = str + namelen;
-	if (*opt == ',')
-		opt++;
-
-	optlen = strlen(opt);
-	if (optlen >= CONSOLE_OPT_MAX)
-		return -EINVAL;
-
-	for (i = 0; i < MAX_CMDLINECONSOLES; i++) {
-		con = &conopt[i];
-
-		if (con->name[0]) {
-			if (!strncmp(str, con->name, namelen))
-				return 0;
-			continue;
-		}
-
-		/*
-		 * The name isn't terminated, only opt is. Empty opt is fine,
-		 * but brl_opt can be either empty or NULL. For more info, see
-		 * _braille_console_setup().
-		 */
-		strscpy(con->name, str, namelen + 1);
-		strscpy(con->opt, opt, CONSOLE_OPT_MAX);
-		if (brl_opt) {
-			strscpy(con->brl_opt, brl_opt, CONSOLE_BRL_OPT_MAX);
-			con->has_brl_opt = 1;
-		}
-
-		return 0;
-	}
-
-	return -ENOMEM;
-}
-
-static struct console_option *console_opt_find(const char *name)
-{
-	struct console_option *con;
-	int i;
-
-	for (i = 0; i < MAX_CMDLINECONSOLES; i++) {
-		con = &conopt[i];
-		if (!strcmp(name, con->name))
-			return con;
-	}
-
-	return NULL;
-}
-
-/**
- * add_preferred_console_match - Adds a preferred console if a match is found
- * @match: Expected console on kernel command line, such as console=DEVNAME:0.0
- * @name: Name of the console character device to add such as ttyS
- * @idx: Index for the console
- *
- * Allows driver subsystems to add a console after translating the command
- * line name to the character device name used for the console. Options are
- * added automatically based on the kernel command line. Duplicate preferred
- * consoles are ignored by __add_preferred_console().
- *
- * Return: 0 on success, negative error code on failure.
- */
-int add_preferred_console_match(const char *match, const char *name,
-				const short idx)
-{
-	struct console_option *con;
-	char *brl_opt = NULL;
-
-	if (!match || !strlen(match) || !name || !strlen(name) ||
-	    idx < 0)
-		return -EINVAL;
-
-	con = console_opt_find(match);
-	if (!con)
-		return -ENOENT;
-
-	/*
-	 * See __add_preferred_console(). It checks for NULL brl_options to set
-	 * the preferred_console flag. Empty brl_opt instead of NULL leads into
-	 * the preferred_console flag not set, and CON_CONSDEV not being set,
-	 * and the boot console won't get disabled at the end of console_setup().
-	 */
-	if (con->has_brl_opt)
-		brl_opt = con->brl_opt;
-
-	console_opt_add_preferred_console(name, idx, con->opt, brl_opt);
-
-	return 0;
-}
diff --git a/kernel/printk/console_cmdline.h b/kernel/printk/console_cmdline.h
index a125e0235589..3ca74ad391d6 100644
--- a/kernel/printk/console_cmdline.h
+++ b/kernel/printk/console_cmdline.h
@@ -2,12 +2,6 @@
 #ifndef _CONSOLE_CMDLINE_H
 #define _CONSOLE_CMDLINE_H
 
-#define MAX_CMDLINECONSOLES 8
-
-int console_opt_save(const char *str, const char *brl_opt);
-int console_opt_add_preferred_console(const char *name, const short idx,
-				      char *options, char *brl_options);
-
 struct console_cmdline
 {
 	char	name[16];			/* Name of the driver	    */
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 420fd310129d..dddb15f48d59 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -383,6 +383,9 @@ static int console_locked;
 /*
  *	Array of consoles built from command line options (console=)
  */
+
+#define MAX_CMDLINECONSOLES 8
+
 static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
 
 static int preferred_console = -1;
@@ -2500,17 +2503,6 @@ static int __init console_setup(char *str)
 	if (_braille_console_setup(&str, &brl_options))
 		return 1;
 
-	/* Save the console for driver subsystem use */
-	if (console_opt_save(str, brl_options))
-		return 1;
-
-	/* Flag register_console() to not call try_enable_default_console() */
-	console_set_on_cmdline = 1;
-
-	/* Don't attempt to parse a DEVNAME:0.0 style console */
-	if (strchr(str, ':'))
-		return 1;
-
 	/*
 	 * Decode str into name, index, options.
 	 */
@@ -2541,13 +2533,6 @@ static int __init console_setup(char *str)
 }
 __setup("console=", console_setup);
 
-/* Only called from add_preferred_console_match() */
-int console_opt_add_preferred_console(const char *name, const short idx,
-				      char *options, char *brl_options)
-{
-	return __add_preferred_console(name, idx, options, brl_options, true);
-}
-
 /**
  * add_preferred_console - add a device to the list of preferred consoles.
  * @name: device name
@@ -3522,7 +3507,7 @@ void register_console(struct console *newcon)
 	 * Note that a console with tty binding will have CON_CONSDEV
 	 * flag set and will be first in the list.
 	 */
-	if (preferred_console < 0 && !console_set_on_cmdline) {
+	if (preferred_console < 0) {
 		if (hlist_empty(&console_list) || !console_first()->device ||
 		    console_first()->flags & CON_BOOT) {
 			try_enable_default_console(newcon);
-- 
2.45.2

[PATCH v3 2/3] printk: Add match_devname_and_update_preferred_console()

[Tony Lindgren]

Let's add match_devname_and_update_preferred_console() for driver
subsystems to call during init when the console is ready, and it's
character device name is known. For now, we use it only for the serial
layer to allow console=DEVNAME:0.0 style hardware based addressing for
consoles.

The earlier attempt on doing this caused a regression with the kernel
command line console order as it added calling __add_preferred_console()
again later on during init. A better approach was suggested by Petr where
we add the deferred console to the console_cmdline[] and update it later
on when the console is ready.

Suggested-by: Petr Mladek <pmladek@suse.com>
Co-developed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Tony Lindgren <tony.lindgren@linux.intel.com>
---
 drivers/tty/serial/serial_base_bus.c |   8 ++-
 include/linux/printk.h               |   4 ++
 kernel/printk/console_cmdline.h      |   1 +
 kernel/printk/printk.c               | 103 +++++++++++++++++++++++----
 4 files changed, 100 insertions(+), 16 deletions(-)

diff --git a/drivers/tty/serial/serial_base_bus.c b/drivers/tty/serial/serial_base_bus.c
index 5ebacb982f9e..2cf86f1ff298 100644
--- a/drivers/tty/serial/serial_base_bus.c
+++ b/drivers/tty/serial/serial_base_bus.c
@@ -210,7 +210,13 @@ void serial_base_port_device_remove(struct serial_port_device *port_dev)
 static int serial_base_add_one_prefcon(const char *match, const char *dev_name,
 				       int port_id)
 {
-	return 0;
+	int ret;
+
+	ret = match_devname_and_update_preferred_console(match, dev_name, port_id);
+	if (ret == -ENOENT)
+		return 0;
+
+	return ret;
 }
 
 #ifdef __sparc__
diff --git a/include/linux/printk.h b/include/linux/printk.h
index 65c5184470f1..7239976698e4 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -60,6 +60,10 @@ static inline const char *printk_skip_headers(const char *buffer)
 #define CONSOLE_LOGLEVEL_DEFAULT CONFIG_CONSOLE_LOGLEVEL_DEFAULT
 #define CONSOLE_LOGLEVEL_QUIET	 CONFIG_CONSOLE_LOGLEVEL_QUIET
 
+int match_devname_and_update_preferred_console(const char *match,
+					       const char *name,
+					       const short idx);
+
 extern int console_printk[];
 
 #define console_loglevel (console_printk[0])
diff --git a/kernel/printk/console_cmdline.h b/kernel/printk/console_cmdline.h
index 3ca74ad391d6..0ab573b6d4dc 100644
--- a/kernel/printk/console_cmdline.h
+++ b/kernel/printk/console_cmdline.h
@@ -6,6 +6,7 @@ struct console_cmdline
 {
 	char	name[16];			/* Name of the driver	    */
 	int	index;				/* Minor dev. to use	    */
+	char	devname[32];			/* DEVNAME:0.0 style device name */
 	bool	user_specified;			/* Specified by command line vs. platform */
 	char	*options;			/* Options for the driver   */
 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index dddb15f48d59..7d91593f0ecf 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2429,18 +2429,23 @@ static void set_user_specified(struct console_cmdline *c, bool user_specified)
 	console_set_on_cmdline = 1;
 }
 
-static int __add_preferred_console(const char *name, const short idx, char *options,
+static int __add_preferred_console(const char *name, const short idx,
+				   const char *devname, char *options,
 				   char *brl_options, bool user_specified)
 {
 	struct console_cmdline *c;
 	int i;
 
+	if (!name && !devname)
+		return -EINVAL;
+
 	/*
 	 * We use a signed short index for struct console for device drivers to
 	 * indicate a not yet assigned index or port. However, a negative index
-	 * value is not valid for preferred console.
+	 * value is not valid when the console name and index are defined on
+	 * the command line.
 	 */
-	if (idx < 0)
+	if (name && idx < 0)
 		return -EINVAL;
 
 	/*
@@ -2448,9 +2453,10 @@ static int __add_preferred_console(const char *name, const short idx, char *opti
 	 *	if we have a slot free.
 	 */
 	for (i = 0, c = console_cmdline;
-	     i < MAX_CMDLINECONSOLES && c->name[0];
+	     i < MAX_CMDLINECONSOLES && (c->name[0] || c->devname[0]);
 	     i++, c++) {
-		if (strcmp(c->name, name) == 0 && c->index == idx) {
+		if ((name && strcmp(c->name, name) == 0 && c->index == idx) ||
+		    (devname && strcmp(c->devname, devname) == 0)) {
 			if (!brl_options)
 				preferred_console = i;
 			set_user_specified(c, user_specified);
@@ -2461,7 +2467,10 @@ static int __add_preferred_console(const char *name, const short idx, char *opti
 		return -E2BIG;
 	if (!brl_options)
 		preferred_console = i;
-	strscpy(c->name, name, sizeof(c->name));
+	if (name)
+		strscpy(c->name, name);
+	if (devname)
+		strscpy(c->devname, devname);
 	c->options = options;
 	set_user_specified(c, user_specified);
 	braille_set_options(c, brl_options);
@@ -2486,8 +2495,13 @@ __setup("console_msg_format=", console_msg_format_setup);
  */
 static int __init console_setup(char *str)
 {
-	char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */
-	char *s, *options, *brl_options = NULL;
+	static_assert(sizeof(console_cmdline[0].devname) >= sizeof(console_cmdline[0].name) + 4);
+	char buf[sizeof(console_cmdline[0].devname)];
+	char *brl_options = NULL;
+	char *ttyname = NULL;
+	char *devname = NULL;
+	char *options;
+	char *s;
 	int idx;
 
 	/*
@@ -2496,17 +2510,23 @@ static int __init console_setup(char *str)
 	 * for exactly this purpose.
 	 */
 	if (str[0] == 0 || strcmp(str, "null") == 0) {
-		__add_preferred_console("ttynull", 0, NULL, NULL, true);
+		__add_preferred_console("ttynull", 0, NULL, NULL, NULL, true);
 		return 1;
 	}
 
 	if (_braille_console_setup(&str, &brl_options))
 		return 1;
 
+	/* For a DEVNAME:0.0 style console the character device is unknown early */
+	if (strchr(str, ':'))
+		devname = buf;
+	else
+		ttyname = buf;
+
 	/*
 	 * Decode str into name, index, options.
 	 */
-	if (isdigit(str[0]))
+	if (ttyname && isdigit(str[0]))
 		scnprintf(buf, sizeof(buf), "ttyS%s", str);
 	else
 		strscpy(buf, str);
@@ -2523,12 +2543,18 @@ static int __init console_setup(char *str)
 #endif
 
 	for (s = buf; *s; s++)
-		if (isdigit(*s) || *s == ',')
+		if ((ttyname && isdigit(*s)) || *s == ',')
 			break;
-	idx = simple_strtoul(s, NULL, 10);
+
+	/* @idx will get defined when devname matches. */
+	if (devname)
+		idx = -1;
+	else
+		idx = simple_strtoul(s, NULL, 10);
+
 	*s = 0;
 
-	__add_preferred_console(buf, idx, options, brl_options, true);
+	__add_preferred_console(ttyname, idx, devname, options, brl_options, true);
 	return 1;
 }
 __setup("console=", console_setup);
@@ -2548,7 +2574,51 @@ __setup("console=", console_setup);
  */
 int add_preferred_console(const char *name, const short idx, char *options)
 {
-	return __add_preferred_console(name, idx, options, NULL, false);
+	return __add_preferred_console(name, idx, NULL, options, NULL, false);
+}
+
+/**
+ * match_devname_and_update_preferred_console - Update a preferred console
+ *	when matching devname is found.
+ * @devname: DEVNAME:0.0 style device name
+ * @name: Name of the corresponding console driver, e.g. "ttyS"
+ * @idx: Console index, e.g. port number.
+ *
+ * The function checks whether a device with the given @devname is
+ * preferred via the console=DEVNAME:0.0 command line option.
+ * It fills the missing console driver name and console index
+ * so that a later register_console() call could find (match)
+ * and enable this device.
+ *
+ * It might be used when a driver subsystem initializes particular
+ * devices with already known DEVNAME:0.0 style names. And it
+ * could predict which console driver name and index this device
+ * would later get associated with.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int match_devname_and_update_preferred_console(const char *devname,
+					       const char *name,
+					       const short idx)
+{
+	struct console_cmdline *c = console_cmdline;
+	int i;
+
+	if (!devname || !strlen(devname) || !name || !strlen(name) || idx < 0)
+		return -EINVAL;
+
+	for (i = 0; i < MAX_CMDLINECONSOLES && (c->name[0] || c->devname[0]);
+	     i++, c++) {
+		if (!strcmp(devname, c->devname)) {
+			pr_info("associate the preferred console \"%s\" with \"%s%d\"\n",
+				devname, name, idx);
+			strscpy(c->name, name);
+			c->index = idx;
+			return 0;
+		}
+	}
+
+	return -ENOENT;
 }
 
 bool console_suspend_enabled = true;
@@ -3318,8 +3388,11 @@ static int try_enable_preferred_console(struct console *newcon,
 	int i, err;
 
 	for (i = 0, c = console_cmdline;
-	     i < MAX_CMDLINECONSOLES && c->name[0];
+	     i < MAX_CMDLINECONSOLES && (c->name[0] || c->devname[0]);
 	     i++, c++) {
+		/* Console not yet initialized? */
+		if (!c->name[0])
+			continue;
 		if (c->user_specified != user_specified)
 			continue;
 		if (!newcon->match ||
-- 
2.45.2

[PATCH v3 3/3] serial: core: Rename preferred console handling for match and update

[Tony Lindgren]

We are now matching and updating the preferred console, not adding it.
Let's update the naming accordingly to avoid confusion.

Suggested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Tony Lindgren <tony.lindgren@linux.intel.com>
---
 drivers/tty/serial/8250/8250_core.c  |  4 ++--
 drivers/tty/serial/serial_base.h     |  4 ++--
 drivers/tty/serial/serial_base_bus.c | 21 +++++++++++----------
 3 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index ff15022369e4..3556fe42ec65 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -42,7 +42,7 @@
 
 #include <asm/irq.h>
 
-#include "../serial_base.h"	/* For serial_base_add_isa_preferred_console() */
+#include "../serial_base.h"	/* For serial_base_match_and_update_isa_preferred_console() */
 
 #include "8250.h"
 
@@ -564,7 +564,7 @@ static void __init serial8250_isa_init_ports(void)
 		if (serial8250_isa_config != NULL)
 			serial8250_isa_config(i, &up->port, &up->capabilities);
 
-		serial_base_add_isa_preferred_console(serial8250_reg.dev_name, i);
+		serial_base_match_and_update_isa_preferred_console(serial8250_reg.dev_name, i);
 	}
 }
 
diff --git a/drivers/tty/serial/serial_base.h b/drivers/tty/serial/serial_base.h
index 743a72ac34f3..a5632eeda250 100644
--- a/drivers/tty/serial/serial_base.h
+++ b/drivers/tty/serial/serial_base.h
@@ -68,12 +68,12 @@ int serial_base_add_preferred_console(struct uart_driver *drv,
 
 #ifdef CONFIG_SERIAL_8250_CONSOLE
 
-int serial_base_add_isa_preferred_console(const char *name, int idx);
+int serial_base_match_and_update_isa_preferred_console(const char *name, int idx);
 
 #else
 
 static inline
-int serial_base_add_isa_preferred_console(const char *name, int idx)
+int serial_base_match_and_update_isa_preferred_console(const char *name, int idx)
 {
 	return 0;
 }
diff --git a/drivers/tty/serial/serial_base_bus.c b/drivers/tty/serial/serial_base_bus.c
index 2cf86f1ff298..391d41ef5942 100644
--- a/drivers/tty/serial/serial_base_bus.c
+++ b/drivers/tty/serial/serial_base_bus.c
@@ -207,8 +207,9 @@ void serial_base_port_device_remove(struct serial_port_device *port_dev)
 
 #ifdef CONFIG_SERIAL_CORE_CONSOLE
 
-static int serial_base_add_one_prefcon(const char *match, const char *dev_name,
-				       int port_id)
+static int serial_base_match_and_update_one_prefcon(const char *match,
+						    const char *dev_name,
+						    int port_id)
 {
 	int ret;
 
@@ -237,7 +238,7 @@ static int serial_base_add_sparc_console(const char *dev_name, int idx)
 		return 0;
 	}
 
-	return serial_base_add_one_prefcon(name, dev_name, idx);
+	return serial_base_match_and_update_one_prefcon(name, dev_name, idx);
 }
 
 #else
@@ -249,7 +250,7 @@ static inline int serial_base_add_sparc_console(const char *dev_name, int idx)
 
 #endif
 
-static int serial_base_add_prefcon(const char *name, int idx)
+static int serial_base_match_and_update_prefcon(const char *name, int idx)
 {
 	const char *char_match __free(kfree) = NULL;
 	const char *nmbr_match __free(kfree) = NULL;
@@ -262,7 +263,7 @@ static int serial_base_add_prefcon(const char *name, int idx)
 		if (!nmbr_match)
 			return -ENODEV;
 
-		ret = serial_base_add_one_prefcon(nmbr_match, name, idx);
+		ret = serial_base_match_and_update_one_prefcon(nmbr_match, name, idx);
 		if (ret)
 			return ret;
 
@@ -277,7 +278,7 @@ static int serial_base_add_prefcon(const char *name, int idx)
 	if (!char_match)
 		return -ENOMEM;
 
-	return serial_base_add_one_prefcon(char_match, name, idx);
+	return serial_base_match_and_update_one_prefcon(char_match, name, idx);
 }
 
 /**
@@ -304,7 +305,7 @@ int serial_base_add_preferred_console(struct uart_driver *drv,
 	const char *port_match __free(kfree) = NULL;
 	int ret;
 
-	ret = serial_base_add_prefcon(drv->dev_name, port->line);
+	ret = serial_base_match_and_update_prefcon(drv->dev_name, port->line);
 	if (ret)
 		return ret;
 
@@ -314,7 +315,7 @@ int serial_base_add_preferred_console(struct uart_driver *drv,
 		return -ENOMEM;
 
 	/* Translate a hardware addressing style console=DEVNAME:0.0 */
-	return serial_base_add_one_prefcon(port_match, drv->dev_name, port->line);
+	return serial_base_match_and_update_one_prefcon(port_match, drv->dev_name, port->line);
 }
 
 #endif
@@ -326,9 +327,9 @@ int serial_base_add_preferred_console(struct uart_driver *drv,
  * This should be only called from serial8250_isa_init_preferred_console(),
  * other callers are likely wrong and should rely on earlycon instead.
  */
-int serial_base_add_isa_preferred_console(const char *name, int idx)
+int serial_base_match_and_update_isa_preferred_console(const char *name, int idx)
 {
-	return serial_base_add_prefcon(name, idx);
+	return serial_base_match_and_update_prefcon(name, idx);
 }
 
 #endif
-- 
2.45.2

Re: [PATCH v3 3/3] serial: core: Rename preferred console handling for match and update

[Greg Kroah-Hartman]

On Tue, Jun 18, 2024 at 07:54:50AM +0300, Tony Lindgren wrote:
> We are now matching and updating the preferred console, not adding it.
> Let's update the naming accordingly to avoid confusion.
> 
> Suggested-by: Petr Mladek <pmladek@suse.com>
> Signed-off-by: Tony Lindgren <tony.lindgren@linux.intel.com>

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Re: [PATCH v3 2/3] printk: Add match_devname_and_update_preferred_console()

[Petr Mladek]

On Tue 2024-06-18 07:54:49, Tony Lindgren wrote:
> Let's add match_devname_and_update_preferred_console() for driver
> subsystems to call during init when the console is ready, and it's
> character device name is known. For now, we use it only for the serial
> layer to allow console=DEVNAME:0.0 style hardware based addressing for
> consoles.
> 
> The earlier attempt on doing this caused a regression with the kernel
> command line console order as it added calling __add_preferred_console()
> again later on during init. A better approach was suggested by Petr where
> we add the deferred console to the console_cmdline[] and update it later
> on when the console is ready.
> 
> Suggested-by: Petr Mladek <pmladek@suse.com>
> Co-developed-by: Petr Mladek <pmladek@suse.com>
> Signed-off-by: Tony Lindgren <tony.lindgren@linux.intel.com>

Looks good and fixes the regression:

Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr

Re: [PATCH v3 3/3] serial: core: Rename preferred console handling for match and update

[Petr Mladek]

On Tue 2024-06-18 07:54:50, Tony Lindgren wrote:
> We are now matching and updating the preferred console, not adding it.
> Let's update the naming accordingly to avoid confusion.
> 
> --- a/drivers/tty/serial/serial_base_bus.c
> +++ b/drivers/tty/serial/serial_base_bus.c
> @@ -304,7 +305,7 @@ int serial_base_add_preferred_console(struct uart_driver *drv,

I was curious whether this patch renamed everything. And it seems
that it did not rename serial_base_add_preferred_console().

>  	const char *port_match __free(kfree) = NULL;
>  	int ret;
>  
> -	ret = serial_base_add_prefcon(drv->dev_name, port->line);
> +	ret = serial_base_match_and_update_prefcon(drv->dev_name, port->line);
>  	if (ret)
>  		return ret;
>  

Honestly, I do not understand what are all these layers for.
Especially, serial_base_match_and_update_prefcon() looks suspicious:

static int serial_base_match_and_update_prefcon(const char *name, int idx)
{
	const char *char_match __free(kfree) = NULL;
	const char *nmbr_match __free(kfree) = NULL;
	int ret;

	/* Handle ttyS specific options */
	if (strstarts(name, "ttyS")) {
		/* No name, just a number */
		nmbr_match = kasprintf(GFP_KERNEL, "%i", idx);
		if (!nmbr_match)
			return -ENODEV;

		ret = serial_base_match_and_update_one_prefcon(nmbr_match, name, idx);
		if (ret)
			return ret;

		/* Sparc ttya and ttyb */
		ret = serial_base_add_sparc_console(name, idx);
		if (ret)
			return ret;
	}

	/* Handle the traditional character device name style console=ttyS0 */
	char_match = kasprintf(GFP_KERNEL, "%s%i", name, idx);
	if (!char_match)
		return -ENOMEM;

	return serial_base_match_and_update_one_prefcon(char_match, name, idx);
}

It seems to try whether c->devname matches a number "X", or "ttySX".
It even tries the sparc-specific transformations in
serial_base_add_sparc_console()

But this is the original format which does _not_ include ":".
It never will be stored in c->devname and will never match.

I think that it has been the case even before this patchset.

I think that we should remove these layers and check just
the "DEVNAME:X.Y" format, aka "%s:%d.%d" [*].


[*] It would be nice to use the same printf format "%s:%d.%d"
    in both serial_base_device_init() and also in the functions
    matching the devname to make it clear that these are
    the same names. Heh, I just guess that these are the same
    names.

Best Regards,
Petr

Re: [PATCH v3 3/3] serial: core: Rename preferred console handling for match and update

[Tony Lindgren]

On Tue, Jun 18, 2024 at 03:51:44PM +0200, Petr Mladek wrote:
> On Tue 2024-06-18 07:54:50, Tony Lindgren wrote:
> > We are now matching and updating the preferred console, not adding it.
> > Let's update the naming accordingly to avoid confusion.
> > 
> > --- a/drivers/tty/serial/serial_base_bus.c
> > +++ b/drivers/tty/serial/serial_base_bus.c
> > @@ -304,7 +305,7 @@ int serial_base_add_preferred_console(struct uart_driver *drv,
> 
> I was curious whether this patch renamed everything. And it seems
> that it did not rename serial_base_add_preferred_console().

Oops, will update the naming for that too.

> >  	const char *port_match __free(kfree) = NULL;
> >  	int ret;
> >  
> > -	ret = serial_base_add_prefcon(drv->dev_name, port->line);
> > +	ret = serial_base_match_and_update_prefcon(drv->dev_name, port->line);
> >  	if (ret)
> >  		return ret;
> >  
> 
> Honestly, I do not understand what are all these layers for.
> Especially, serial_base_match_and_update_prefcon() looks suspicious:
> 
> static int serial_base_match_and_update_prefcon(const char *name, int idx)
> {
> 	const char *char_match __free(kfree) = NULL;
> 	const char *nmbr_match __free(kfree) = NULL;
> 	int ret;
> 
> 	/* Handle ttyS specific options */
> 	if (strstarts(name, "ttyS")) {
> 		/* No name, just a number */
> 		nmbr_match = kasprintf(GFP_KERNEL, "%i", idx);
> 		if (!nmbr_match)
> 			return -ENODEV;
> 
> 		ret = serial_base_match_and_update_one_prefcon(nmbr_match, name, idx);
> 		if (ret)
> 			return ret;
> 
> 		/* Sparc ttya and ttyb */
> 		ret = serial_base_add_sparc_console(name, idx);
> 		if (ret)
> 			return ret;
> 	}
> 
> 	/* Handle the traditional character device name style console=ttyS0 */
> 	char_match = kasprintf(GFP_KERNEL, "%s%i", name, idx);
> 	if (!char_match)
> 		return -ENOMEM;
> 
> 	return serial_base_match_and_update_one_prefcon(char_match, name, idx);
> }
> 
> It seems to try whether c->devname matches a number "X", or "ttySX".
> It even tries the sparc-specific transformations in
> serial_base_add_sparc_console()
> 
> But this is the original format which does _not_ include ":".
> It never will be stored in c->devname and will never match.

Good catch, this won't do anything now with console_setup()
checking for ":" for deferred consoles. So we should revert commit
a0f32e2dd998 ("serial: core: Handle serial console options").

> I think that it has been the case even before this patchset.

For the earlier case, I tested things with serial handling removed
from console_setup() to let the serial layer handle the quirks.

With the new handling, we could just eventually defer the serial
consoles in console_setup(), and let the serial core do the quirk
handling. No immediate need for that though, that would be just
longer term clean-up.

> I think that we should remove these layers and check just
> the "DEVNAME:X.Y" format, aka "%s:%d.%d" [*].

Yes let's revert the quirk handling.
 
> [*] It would be nice to use the same printf format "%s:%d.%d"
>     in both serial_base_device_init() and also in the functions
>     matching the devname to make it clear that these are
>     the same names. Heh, I just guess that these are the same
>     names.

I'll do a separate clean-up patch for that, and that can then
be used for the match() too eventually.

Regards,

Tony

Re: [PATCH v3 3/3] serial: core: Rename preferred console handling for match and update

[Tony Lindgren]

On Wed, Jun 19, 2024 at 07:39:04AM +0300, Tony Lindgren wrote:
> On Tue, Jun 18, 2024 at 03:51:44PM +0200, Petr Mladek wrote:
> > It seems to try whether c->devname matches a number "X", or "ttySX".
> > It even tries the sparc-specific transformations in
> > serial_base_add_sparc_console()
> > 
> > But this is the original format which does _not_ include ":".
> > It never will be stored in c->devname and will never match.
> 
> Good catch, this won't do anything now with console_setup()
> checking for ":" for deferred consoles. So we should revert commit
> a0f32e2dd998 ("serial: core: Handle serial console options").

Heh actually we can revert a lot more, basically leaving only
the renamed serial_base_match_and_update_preferred_console().

Regards,

Tony

Re: [PATCH v3 3/3] serial: core: Rename preferred console handling for match and update

[Petr Mladek]

On Wed 2024-06-19 10:17:46, Tony Lindgren wrote:
> On Wed, Jun 19, 2024 at 07:39:04AM +0300, Tony Lindgren wrote:
> > On Tue, Jun 18, 2024 at 03:51:44PM +0200, Petr Mladek wrote:
> > > It seems to try whether c->devname matches a number "X", or "ttySX".
> > > It even tries the sparc-specific transformations in
> > > serial_base_add_sparc_console()
> > > 
> > > But this is the original format which does _not_ include ":".
> > > It never will be stored in c->devname and will never match.
> > 
> > Good catch, this won't do anything now with console_setup()
> > checking for ":" for deferred consoles. So we should revert commit
> > a0f32e2dd998 ("serial: core: Handle serial console options").
> 
> Heh actually we can revert a lot more, basically leaving only
> the renamed serial_base_match_and_update_preferred_console().

I wonder if it would be cleaner to revert all patches adding
the feature and then add back just the minimalist solution.

Best Regards,
Petr

Re: [PATCH v3 3/3] serial: core: Rename preferred console handling for match and update

[Tony Lindgren]

On Wed, Jun 19, 2024 at 02:08:40PM +0200, Petr Mladek wrote:
> On Wed 2024-06-19 10:17:46, Tony Lindgren wrote:
> > On Wed, Jun 19, 2024 at 07:39:04AM +0300, Tony Lindgren wrote:
> > > On Tue, Jun 18, 2024 at 03:51:44PM +0200, Petr Mladek wrote:
> > > > It seems to try whether c->devname matches a number "X", or "ttySX".
> > > > It even tries the sparc-specific transformations in
> > > > serial_base_add_sparc_console()
> > > > 
> > > > But this is the original format which does _not_ include ":".
> > > > It never will be stored in c->devname and will never match.
> > > 
> > > Good catch, this won't do anything now with console_setup()
> > > checking for ":" for deferred consoles. So we should revert commit
> > > a0f32e2dd998 ("serial: core: Handle serial console options").
> > 
> > Heh actually we can revert a lot more, basically leaving only
> > the renamed serial_base_match_and_update_preferred_console().
> 
> I wonder if it would be cleaner to revert all patches adding
> the feature and then add back just the minimalist solution.

Yeah let's do that. Otherwise it's hard to see what's going on :)

Regards,

Tony